FlatBuffers发布时,顺便也公布了它的性能数据,具体数据请见Benchmark。
它的测试用例由以下数据构成"a set of about 10 objects containing an array, 4 strings, and a large variety of int/float scalar values of all sizes, meant to be representative of game data, e.g.
a scene format."
我感觉这样测试如同儿戏,便自己设计了一个测试用例,主要关注CPU计算时间和内存空间占用两个指标,参考对象是protobuf。
测试用例为:序列化一个通讯录personal_info_list(table),通讯录可以认为是有每个人的信息(personal_info)的集合。每个人信息personal_info(table)有:个人id(uint)、名字(string)、年龄(byte)、性别(enum, byte)和电话号码(ulong)。本来我想用struct表示personal_info(table),但是struct不允许有数组或string成员,无奈我用table描述它了。相应的idl文件如下:
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namespace as.tellist;
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enum GENDER_TYPE : byte
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{
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MALE = 0,
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FEMALE = 1,
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OTHER = 2
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}
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table personal_info
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{
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id : uint;
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name : string;
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age : byte;
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gender : GENDER_TYPE;
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phone_num : ulong;
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}
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table personal_info_list
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{
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info : [personal_info];
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}
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root_type personal_info_list;
因为要以protobuf做性能参考,列出protobuf的idl文件如下:
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package as.tellist;
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enum gender_type
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{
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MALE = 0;
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FEMALE = 1;
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OTHER = 2;
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}
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message personal_info
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{
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optional uint32 id = 1;
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optional string name = 2;
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optional uint32 age = 3;
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optional gender_type gender = 4;
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optional uint64 phone_num = 5;
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}
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message personal_info_list
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{
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repeated personal_info info = 1;
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}
若用C的struct描述对应的头文件(其对应的程序称之为“二进制”),如下:
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#ifndef __TELLIST_H__
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#define __TELLIST_H__
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enum
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{
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GENDER_TYPE_MALE = 0,
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GENDER_TYPE_FEMALE = 1,
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GENDER_TYPE_OTHER = 2,
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};
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inline const char **EnumNamesGENDER_TYPE()
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{
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static const char *names[] = { "MALE", "FEMALE", "OTHER"};
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return names;
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}
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inline const char *EnumNameGENDER_TYPE(int e)
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{
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return EnumNamesGENDER_TYPE()[e];
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}
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typedef struct personal_info_tag
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{
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unsigned id;
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unsigned char age;
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char gender;
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unsigned long long phone_num;
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char name[32];
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} personal_info;
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typedef struct personal_info_list_tag
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{
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int size;
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personal_info info[0];
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} personal_info_list;
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#endif
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测试时,在内存中构造37个personal_info对象,并序列化之,重复这个过程100万次,然后再进行反序列化,再重复100万次。
测试结果如下(补充:tellist_pb是protobuf测试程序,tellist_fb是FlatBuffers测试程序,tellist_fb是二进制测试程序,):
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测试环境:12Core Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
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free
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total used free shared buffers cached
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Mem: 66081944 62222028 3859916 0 196448 43690828
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-/+ buffers/cache: 18334752 47747192
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Swap: 975864 855380 120484
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protobuf三次测试结果:
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bin/tellist_pb
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encode: loop = 1000000, time diff = 14210ms
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decode: loop = 1000000, time diff = 11185ms
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buf size:841
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bin/tellist_pb
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encode: loop = 1000000, time diff = 14100ms
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decode: loop = 1000000, time diff = 11234ms
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buf size:841
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bin/tellist_pb
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encode: loop = 1000000, time diff = 14145ms
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decode: loop = 1000000, time diff = 11237ms
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buf size:841
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序列化后占用内存空间841Byte,encode平均运算时间42455ms / 3 = 14151.7ms,decode平均计算时间33656ms / 3 = 11218.7ms
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flatbuffers三次测试结果:
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bin/tellist_fb
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encode: loop = 1000000, time diff = 11666ms
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decode: loop = 1000000, time diff = 1141ms
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buf size:1712
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bin/tellist_fb
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encode: loop = 1000000, time diff = 11539ms
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decode: loop = 1000000, time diff = 1200ms
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buf size:1712
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bin/tellist_fb
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encode: loop = 1000000, time diff = 11737ms
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decode: loop = 1000000, time diff = 1141ms
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buf size:1712
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序列化后占用内存空间1712Byte,encode平均运算时间34942ms / 3 = 11647.3ms,decode平均计算时间3482ms / 3 = 1160.7ms
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二进制三次测试结果:
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bin/tellist
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encode: loop = 1000000, time diff = 4967ms
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decode: loop = 1000000, time diff = 688ms
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buf size:304
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bin/tellist
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encode: loop = 1000000, time diff = 4971ms
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decode: loop = 1000000, time diff = 687ms
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buf size:304
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bin/tellist
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encode: loop = 1000000, time diff = 4966ms
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decode: loop = 1000000, time diff = 686ms
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buf size:304
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序列化后占用内存空间304Byte,encode平均运算时间14904ms / 3 = 4968ms,decode平均计算时间2061ms / 3 = 687ms
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测试环境:1 Core Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
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free
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total used free shared buffers cached
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Mem: 753932 356036 397896 0 50484 224848
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-/+ buffers/cache: 80704 673228
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Swap: 1324028 344 1323684
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protobuf三次测试结果:
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./bin/tellist_pb
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encode: loop = 1000000, time diff = 12451ms
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decode: loop = 1000000, time diff = 9662ms
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buf size:841
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./bin/tellist_pb
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encode: loop = 1000000, time diff = 12545ms
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decode: loop = 1000000, time diff = 9840ms
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buf size:841
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./bin/tellist_pb
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encode: loop = 1000000, time diff = 12554ms
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decode: loop = 1000000, time diff = 10460ms
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buf size:841
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序列化后占用内存空间841Byte,encode平均运算时间37550ms / 3 = 12516.7ms,decode平均计算时间29962ms / 3 = 9987.3ms
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flatbuffers三次测试结果:
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bin/tellist_fb
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encode: loop = 1000000, time diff = 9640ms
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decode: loop = 1000000, time diff = 1164ms
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buf size:1712
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bin/tellist_fb
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encode: loop = 1000000, time diff = 9595ms
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decode: loop = 1000000, time diff = 1170ms
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buf size:1712
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bin/tellist_fb
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encode: loop = 1000000, time diff = 9570ms
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decode: loop = 1000000, time diff = 1172ms
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buf size:1712
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序列化后占用内存空间1712Byte,encode平均运算时间28805ms / 3 = 9345ms,decode平均计算时间3506ms / 3 = 1168.7ms
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二进制三次测试结果:
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bin/tellist
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encode: loop = 1000000, time diff = 4194ms
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decode: loop = 1000000, time diff = 538ms
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buf size:304
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bin/tellist
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encode: loop = 1000000, time diff = 4387ms
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decode: loop = 1000000, time diff = 544ms
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buf size:304
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bin/tellist
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encode: loop = 1000000, time diff = 4181ms
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decode: loop = 1000000, time diff = 533ms
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buf size:304
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序列化后占用内存空间304Byte,encode平均运算时间12762ms / 3 = 4254ms,decode平均计算时间1615ms / 3 = 538.3ms
上面的二进制程序的结果无论在内存空间占用还是cpu计算时间这两个指标上都是最快的。但本文只讨论FlatBuffers和protobuf,所以不让它的结果参与比较。
从以上数据看出,在内存空间占用这个指标上,FlatBuffers占用的内存空间比protobuf多了两倍。序列化时二者的cpu计算时间FB比PB快了3000ms左右,反序列化时二者的cpu计算时间FB比PB快了9000ms左右。FB在计算时间上占优势,而PB则在内存空间上占优(相比FB,这也正是它计算时间比较慢的原因)。
上面的测试环境是在公司的linux server端和我自己的mac pro分别进行的。请手机端开发者自己也在手机端进行下测试, 应该能得到类似的结果。Google宣称FB适合游戏开发是有道理的,如果在乎计算时间我想它也适用于后台开发。
另外,FB大量使用了C++11的语法,其从idl生成的代码接口不如protubuf友好。不过相比使用protobuf时的一堆头文件和占18M之多的lib库,FlatBuffers仅仅一个"flatbuffers/flatbuffers.h"就足够了。
测试程序已经上传到百度网盘,点击这个链接即可下载。欢迎各位的批评意见。